extending stock radius arm

[379bobo]

I have a 93 ranger 4.0 5 speed 4x4 Lifted 4 inches. I did a lot of research on extending the oem radius arms couldn't find anything into detail. I was wondering how much l Should extend the arms. Also how much caster to add into the arm. And how would I go about measuring to add the caster. I was Hoping not to have to do anything with the trans crossmember an to use the oem radius arm c rossmember if possible. I appreciate all the help in advanced...

 

[YungICY]

I'm not real educated on the topic but I'm getting ready to do the same for my 85 2wd prerunner. In the prerunner community the general consensus is that radius arms need to be extended at least 12" which would land it right on or right before the trans cross member. As far as using the stock radius arm cross member and an extended radius arm, that doesn't seem plausible or possible to me. However you could probably use a drop down bracket of some sort if you're just going for height with your lift (vs full beam travel on my prerunner.) and for caster you want somewhere between 4 and 8 degrees.



If you want a fairly easy design for radius arms just do a google search for extended radius arms and click on the images tab.


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[4x4junkie]

12" is what I extended mine. They ended just in front of the stock trans crossmember. I used 20" lengths of 2" .250" wall DOM tubing. IIRC, I added about 5° caster to them.

 

[379bobo]

4x4junkie how did you add the 5° in to the arm.

 

[YungICY]

I'm just speculating but you take the caster angle from the beam ( imagine a straight line through the beam where your ball joints are mounted/mount to. That is your caster angle.) there are several ways to change this angle. You can either put a bend in your new radius arms to make caster, or if you're making an arm with two pieces of tube you can make the top one shorter/bottom one longer.



Do a google image search for extended radius arms and you can get several good visual ideas on how to do this via different designs. And if you want to get wild do the same search for "radius arms with adjustable caster" there are a could of really good designs there as well.


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[4x4junkie]

I set the suspension to it's proper ride height (axle beam pivots 1" above wheel hub centerline) and then positioned the beam with the arm body attached so that the beam was square with the ground. With the tube section mounted in the frame bracket I then tack-welded the tube into the arm. 5° is what I recall it ended up being (and should work with any lift height from 3-5", as you can still adjust it using the camber/caster bushing built into the beam).

Like YungICY says, you can also reference a line from where the arm is attached at the axle beam to the bushing end of the arm. If you're using a single tube to extend the arm as i did, move the tube's position up until you have added 5° to it as measured at the beam.